SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '566d4939fae8a5556d02012bfdf2f9beba17f034c1998539b89de3b9a3583c23' 
  AND token = 'Lj4alpozQcztMOhRF8tqLrRZZM0npZhl+xyQxmgOHPo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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