SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68d9bb9cccba7db1a8aaa4b50bcf3df7f474025815f16a65684c5644cfc91f42' 
  AND token = 'K21mmhkPY7vRSnrZyR+PXvq0IBg0w4xaVHBH3Z55zno=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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