SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a91d9ecd54809878ea215ee1e79115a9b2cd2c66efcf271e1decacdfddcef40f' 
  AND token = 'FEQMWKYfkE1ONL34566so3gIvdzHCBeUKDBSvSXEh3c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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