SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31de84510189359fb78af95dc37509edd33c50537d68f69e98df8475ad1734d6' 
  AND token = 'cJyq26s32O80p3647uGLBKgahVQmAQ5QXbGKkfmRXG4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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