SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e286338f902b0472bb2df56cd540b739c243045894e06f4cd4dcf37d52f1668' 
  AND token = 'tz7gOYiF8XAVmrVp6He1rs4qz5FjcBl4kOQLjscG0Dg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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