SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ddaa670c23f18324a5a2800cba47b1786a9dd3a9efc9bf6a5cd75bfc89e8373' 
  AND token = 'ZWBtv21MQxMeNOrXk4WI6LWOphDwfyioR+NCEWMQ95M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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