SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f759569eda1c3a602b62db3656d2062861ab9b7274c8ac94311e705d5dcbe1c0' 
  AND token = 'u+Mktqi3LwgB44ZbAmZ2+v9tirBrX3Pw+oYFzXnS1mQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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