SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '353cb2870fa046f422554c0528564cc2c2b24c277f181cde6c5a87272a05b923' 
  AND token = 'L6kzlTs3k/JHqwIg60V+IW49gGK7fJjmbY2MFCL4BMU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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