SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7637bd690dc7d0380127437334a86543d516d378723c721519b369cb3526d6f6' 
  AND token = 'oTkpwijGefyoVfbxXKX2fdW3+cE+tI4YgvmoydqrObs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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