SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38d8b4573fba5ee22fbedda8241838cfe3c63a0cb56c0f45a81e2edb367a80dc' 
  AND token = '607LgYtuhAUuZW7JwDkqejxJDny9CRUjBRhqfPYbqPM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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