SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'db26ee8fe0834b1794d9426f7320eeeb138746d76a23d6ffc63a2093db0c0201' 
  AND token = '55VlKtgwDW9UQXIPWZc/mW45Y3LJeOsxIjXfoM/SHD8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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