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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f38ad435f0363fb1f24aba53854ad897edc076ca21d4b6997d0c17bf54fe0251' 
  AND token = 'A3brObxnex7NkpkV9nON5CTXeuFTUgmnBWp/raJqhCw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}