SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c309d50dc9c7ad3506bd00e014fc82e4a67ccb1fd2bdf3a848338f0ba2162795' 
  AND token = 'ilPBBQFxJxVRN0gkx9pcOkhqYB0SvszthwKi+JylPKM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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