SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51f51f9c48a8e980d7a13206011a03384df99f357f23062cdeb07c22f71ac857' 
  AND token = 'YpZuAr5pMfkolPg4kQ0UgMhi+y+SNns1K6DgTqi09YY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00050

JSON explain

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