SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9ce3b41ce4af64ed0a68650c2b64d3d8846f40b10f7e2f9b58cb3df93b2c257' 
  AND token = '0nWZhrGxfYvjh8S6M/Bvvb3PxXjMNi9lYlVe3vgvBWU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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