SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27753262504dad874eb688d55f6cd1f33bfcdc6d35278f1262a40a35d8083c28' 
  AND token = 'n7StDfhwofFVZbyzFQFw3/NEU9kjjjAmY2z9v6+0Qs4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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