SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be9a90f23c63a3a649b68e492a7140ee3f336766d86856f255ba360e8f4e5997' 
  AND token = 'WZqWU5RzRVWj8BAonjg/KLGItSm3CC/qmcAlNzrsXlc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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