SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df27c36f5f196d430599034443661a6016c1dcbd7a7057b543a8c2458441d301' 
  AND token = 'bKxWxvoWDxOqh0CrizulEXzIGE59Hg0ptoQRujliwHo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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