SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3d8793454dfbc1746a2c7cf757fa354019bbc1f09a1253d8730c9eea8f988a5' 
  AND token = 'xnA8z33gN3pds6mKTR1JaWEUMQ5wTByrqJLpJUzXbzY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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