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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '853beeaa4d2602fe6d8b8ab90a1d1fbb62ac58f5ed8644d13764b9792b6968b4' 
  AND token = 'mLviCHOrP0msiGIMjoCPfiHzTx1ISRmdsFb1em4mpgA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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