SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d8ad3d670baa4b7bb9c295d2a32ec9235799694671b007be5f003a1d7697f5a' 
  AND token = '8tCUMmd/AVHEIBeP3UzcWeNtoivjNxcoSN8PQBWAPXE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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