SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0dc539e7f13c2db66dd42bd971075a0733c4e4d72c038b4596a5314806459046' 
  AND token = 'qILudcBGrJPz3mKfGg1CjXZ6rfK8gizLFTfol+Wf5vg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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