SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bce39ce53800b357198107839772a8e8300f287b41253a7b1f211d43da9205b7' 
  AND token = '5oS7InpH2PFDro97dgrvUpnOGdwOLgv13Q2+rYHw4Hg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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