SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c7a2bd9f577bf09068295ac20bdf69833db8457d671261d40c396131a5089015' 
  AND token = 'eA1VDdpQcOwBhPp3Hn4Cxyk3RHv9A0UfpFFn4hazKGo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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