SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc8fea3c371a948eb488e0def7ef09492fe662a5f008916c8e05c428208e4169' 
  AND token = 'OAFfsuTTuPh1a/kmRsuIndkEwA22ydej9smSxtSEqUI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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