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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a7c3b5e8acce6f754ffa543190c25ebd48ac0fa2a69f0bedf78ae776f8bbf19d' 
  AND token = '6lOpJlBKoekysUcaOAa9X7UdrC/hUOXt9u/gS62epac=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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