SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a7052a37f15cba0de756897638280ef9721c2fcf8bc5b1ca701f3db3d0151980' 
  AND token = '89/sYJsR3rANQfHL6oyFvjK1rSZd0zC+qFYNv+T+Sv4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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