SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '57691f3be8c19624f4692e87450550823a50dcf87882785d66467da3f55905b3' 
  AND token = 'NjKJPwsZpzRFyk2oqRkcmVcGXAOn6G8RXpJZBiu0LlM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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