SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e99d34b50d495209e2b7467a4e8aac597dfbeb65cd0f46290858a3ecbba87b57' 
  AND token = 'sCKUSWeXPhmG4ExVVbBp3EN09nc9wCCPzcpAdgGfoBk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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