SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '44d260f2d859e6097569af359c649d4cbda305ace79867a0327764c8556a66c2' 
  AND token = '0rM4VWTkKE4VkPbQNT6Cpqn+mdIyysG8bpP1US93JWo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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