SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e840db49b875c662ccf1e8495d053d9d205a966c4b09c16256199acd1dba983' 
  AND token = 'mbPUyfAUkgS73eb7A3pT9xkCv6P9VLyH4i6TjEz4dxs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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