SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b8d14f7ab90b36e1e891410d5f249edec8c11e2b2d1f471979b76ebff852ca9' 
  AND token = 'gjZOlVF/1ya82WN8PIEV0eWnFoIzbYNg4Eot1KciFR4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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