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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03e75ab0b7088f49cb7ff0d323b8c218b60bece8aa818d16e9bfbfd43dc52201' 
  AND token = '7wbNve5CJJUztJ2UYO5AEOl+YgXvNkUt36Elkc1gHiE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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