SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a571de2ec94eb2c5de46ec3dcbfe591e5b466945048f799edd43671d50d9d876' 
  AND token = 'knGLLqzLU/18henQKda/nQFTuQ0PYSoRF5Jjc1lvtoQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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