SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7575e07b431aba808d0ee375aff2f1d85ca7bcf70216a6edb897780fe7aab121' 
  AND token = 'FmNqcQz2AIth02YfS8vQPPWdAxcEZNGqQhtI1ZTjdJs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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