SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0b3d31e42c2473479d27e3ddc85549c21bec9625baebf327491ad8c44dd2612' 
  AND token = 'v84UFZPkwOerDszmdLZtwbL+6aUpIRp89t6y8hGjhBk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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