SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e58218a2f2e84b296a3484b5e8fb295f142d7e7650875e079c46c73d29378c2e' 
  AND token = 'cykPXvaPkZl6bgwgAAG1Wz4VCi+mfFIjdOTUPIsqJYY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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