SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a1b0fb9c1ec4a883ea5d04bf3a05391d293db292647521a772d4b84313250f9' 
  AND token = 'rJUHCPDid5dQrzWYSvikiAlrVl9mQxDnIOAbRIdTNN8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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