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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '847e83272ec8ec5633296fedcd447bb6cd261330f1491aaf4020a5dcbb9c8486' 
  AND token = 'MzK7sMN74sKUjnaC4TFfZ4BC40GHwj40/F6oeMoE+YE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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