SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b257ee31439855ebdcbe87613142460e7a45f3c9910d16d9684f4c2dd375476' 
  AND token = '4HPgCCKmuL6jNgnP3WJsweXMiKwFCqnocILJsmATGjo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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