SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '919f79b9ac5dc001264643b650fd2b65a7728cab4f8fd3f2dc70545f830c87d2' 
  AND token = '+j4JWtKAdguzzmIpbDGDQw7E+rFk7irGjfmw5X1gQpI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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