SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd9c8619c22792ddf0c2c892b2f273f77c360f76fdb510240a06b4838af2a47e6' 
  AND token = 'lE8HhnWAcvl1hsjVFRgZSS7xuznaCOkQYypjLhMAYYc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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