SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f8899905c1921f6ab1408b6144977abd7bf910dfec374a75368a639c187ac5e' 
  AND token = 'krN3JxZun5VeItEJmwlCMzzeFyyaLk1s59exZ9LnpXY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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