SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8bbc799ed456c87c2806c241c6379cb04da9e6f7d5b250471c05a4585ec25518' 
  AND token = 'tEC3pJJyiYuV6xlSp6IauBUDBBav17hhcS6w2MMSwag=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}