SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fec15119d04255617c8e68a820700962ee0a77decf2adc9a58254d9d689c4b6f' 
  AND token = 'YJtB93jmDHBfgRFyWEAV4lDbkI1N4imu9//ql+H34Mc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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