SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78d9e86f1a6a87929575e9405396e3bf64745d6ef4736f3efd9c14fdc0c3886b' 
  AND token = 'tUQE07XHFJvXGaMNPqNGv3l+i/rmbpCMXSGlfO4/n0g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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