SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '105e184357c66fc3b50da6c9bb29b3feb5dda81a1ba09b129f6a7c826b89d721' 
  AND token = 'DWMlqAJ1PShEmDj3NL8wZ+hg//Rlol+f0juG9BB/VBw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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