SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20fb050f72971e003d7e4e6b3c2f85378361e89cfd3a34a1a318e54b6abdfe7f' 
  AND token = '4aDgDgpk73kyafvIySPWa5RbHfaEDZrGtJZSVOniWwY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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