SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37e7cb3244c816c1fb67ca52ce974769c59d0fa1d18aeb4bed4b24c0854cad09' 
  AND token = 'trdNkSb3Kge4nRw67oZgYhn5oLNRehQHrZ6UxuULnAM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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