SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '857fd6b698bce913e045c5e5b463cd22d39ec55150599e527ea5773e1fbf679b' 
  AND token = '+CNB6tduYmSaryUqtp98jvlsMlHlW+d0wXwCqoffciw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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