SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac57a44539081098b01d68f350c7b40928da432c3dc59d099cc9cb92381ee6e9' 
  AND token = 'RFhLw+sSMVeYhas8ozkkVbPv9Q23bg/Ls3Uk5+fZc6c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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