SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a65b291d649b41e051a4a2ffcd552c6fb3813ebca6de7659223e2fd7fe51c289' 
  AND token = 'MRZX/WiI07sjvmRhLxaqQlNH+H1AC5VckCwdtxczlHs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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