SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f94b80a600432c6e8278459d5671656fa22c8df8c2c9a7cb19042676c0d1d29' 
  AND token = 'Btife7PQp4cmXdIQK3vWkQhhkLQpQWcXi+JI2x9QKSY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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