SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92796e9ef530060c34c25dbbb32be0e23c6dc3d8d2cc711d58066e140117389e' 
  AND token = 'k/x1GWOVH1SkcMTBYzaCMT/uFAQEPiWs/gbTGJNRWTk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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