SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21486d9577f97609645747552f298478c285a434dba10530ade0b3d666c3eff7' 
  AND token = 'cIAU98ulv1mEyUUMXr1CO3jK9pzGtDI2mdp4TWBo7ys=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00012

JSON explain

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