SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50c149306f7addd391fd170e4cf775c0c9f45f323bd19605eccfd78873c98350' 
  AND token = 'WEl9Kv871DKZPBNCKemgkVQF7K7UFd7Tz2tHctmi8pg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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