SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6ff337219b9b4d0992ce2d560fe822a83eba61b31f678b3a9f1f8da223095f3' 
  AND token = 'OQ9mqBFsqGQxY9VZF2jP6o2WzPgIGxqHo2UsDzBTY7I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00059

JSON explain

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