SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c8321d679364f45f189fdfe86f07e1889f3b6a22eb3211e1ef5a4fae9de75c1' 
  AND token = '1jND/lK9DttDcnvLGLhL1zFXYh9RCmpkhH86inK2Zaw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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