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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '257642cd5649db811e97b2d05dfdd33b29751ee7dd57f1ce8cdaa73d761243bc' 
  AND token = '6CrHcc19jFAj9fw9tNeYb07T+xvcuiBaD405gEwDVyE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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