SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2c0083cbd97e761d374851941a43e4e80ea43a085feaed849a98d6d748e6e46' 
  AND token = 'wjtGilO7dAv2U4l19kSjPbREgtVpomXfV2HTSkVQjXo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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