SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e2a40c45124a2d6aec20d478901396d17b8e1fbbb33d172a03d69625a10da9c' 
  AND token = '90DpKl3NlHfcrqfGpVtCK+TH/y6BPz+p8+uQnYk9vto=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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