SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52a15eb68630f971b6dfef98ef24734d14b2cbd57d48cfecb4bef193b031f5f1' 
  AND token = 'SrPuo4UU3hXlbYvCqWlUvQt+cP6y//hSwJ6xUVbJ8KE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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