SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50107cd196747e23a03e06a2a7ac52cbd6f9efedd65066545f37bb24e7b43f34' 
  AND token = 'z6iP8M5e7IVAkj5VYLE3zrsU+ZY2gcgPlZtzvsTJRQM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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