SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f3de19fa374f91c3b5ed631f52548471e97f707adeafe799888c4219c18057b' 
  AND token = 'vf/oBCftzXoymMQl8fGMwrdk7mnyDZfK7Bd8R+VYc0k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}