SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '900efbdf1f3b8d829c5d5fdc64dc1673611df279d1329e38122fcf3b187fd2dc' 
  AND token = '1OM4C5vi4kgip5Gy0RaWYsyLOIwi7Ez+PIEAkQR3D4k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}