SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4f71a9d0c575719bc46c288e2bcebe605af1072c0c35bd3f621f26011919370' 
  AND token = 'lwLxQtXuP2gaxOPPQlB4TEvqKsTwwnkULIWI2ZncfBI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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