SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ad174122085f342843edc298567028e2e1dbabddc8df08c72bce9e894f9d4e7' 
  AND token = 'vHcnUYtsK6yB6Jywvv//gggoyNSIB1Tq8XD2gaZ+shI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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