SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb1eaae2cf9b99fd7e464bd8c40fb370550751d53e50c19acacbb662591e34f9' 
  AND token = 'uzfGfJFg7JqztfWPCTI3lj2dZZE9nUgQh8dlCoHw3Ts=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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