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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5312881e68da586fa55ac8bf4ea1debc12a741b6b91274b1d665f7d7e38184b8' 
  AND token = 'wbv9+BSSKNVzxTw+gMO6oTwXvZTaFwtT+q3mLAwcHZY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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