SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '34761d33dcb32e02dda648052f7a571d3f27ab1de171ebd3afaf937216417999' 
  AND token = 'nUXrSZekdKtxWuqNyQxgtYoDzQm1pl+9y+WVMm50T3Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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