SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28c26e03df02b536c8650e78f57b10917f61a1987b5849efe2c04e5f8f1aac8b' 
  AND token = 'Gv2RzrwAgZkhdk/xrZ4FThI4vMU6sVwdmsMo7Q05FBo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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