SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f875115cd0295011142b2e2e93d5adef8b7d7780ac2dc80b010321bbfc147d63' 
  AND token = 'l6zzTFoEzf4bn2yyewVBBnyQJJqwYhBCiZGeWVRLaFk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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