SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ce31064f389116e041bb24b162c1a932b423525b2cc5deae17fab0c6a4ef921' 
  AND token = 'ZZqmm6eBBvurzRmXzUy8XMFHcKkovWk37JX9sCDPCWk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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