SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '346942040306c5796da90f1badeabe1055232b29037dfac8e5e31d682dd430c5' 
  AND token = 'yFD6pIeZUfPTaSXpklzdpm8RSWciiiiotQHr8yHPaG8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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