SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8eb368bbc5f2936d6122e1262ba9a8c66b98ecd177ec3c11974153ef33fb2136' 
  AND token = 'PLaggK+oy804l5qXchh9ffmiRnr0PeVaDsrNUNt+Ff8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}