SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f411bedb6a16fc44556a83968dca2725c9294a94666624bcf08d070074d7f678' 
  AND token = 'k7NIfc4HMV875w/VWMqwu1Tna0RTWH6q65BZCUlVvR4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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