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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c8ce6f59920e3cc1aaac6b7b361ee8ee7649ca8f254e1b4750c4568e0b095156' 
  AND token = 'Bd3OBKk6cU2FTNePCmeJo50bTsaCqUHdjmLdcu52yHY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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