SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f1b2c49e145a497def6d6da96380c2c82f6f8b295de837c4b49e9e3b9ab156d1' 
  AND token = 'oYCnN2SlGIFda+ProritZTrntUikrMbmpt4izz8JPL0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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