SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3708598eb2d42592cda3a791e14ee4ddc3ec8918e8edd67c76e6708b5311700f' 
  AND token = 'UzVFpkxlH5hHzJCC7VpuupdizZPAbEul2PmmzYK8mVA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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