SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c1c72466f1185d3d8243cd293438aa36362c6f9851ddad4e936f340c075cfd0' 
  AND token = 'KQYMslwWER2XexECulepxIJ7fjHNHCt1zfUWImAFx4o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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