SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56c7486713ffaaff5504a124a77f0afebaa9215f31f206c0ae6896f26765e2fe' 
  AND token = '3MIcSLk9TflHx1/CN3I+zaG3Cj6JhEcNb+gpgrPuVE4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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