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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2183e24261d2bf1b5f68dde4d30144641398d85816d971d382a71077c59383a4' 
  AND token = '/U75KpBPTcLfyYxh1hAF3kte/+y3+C5SnLEe8oejr6M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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