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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3904089e0e61a098bfea41538c1c9f05c8daae852f640858f36d7ef9754d0941' 
  AND token = 'p2oCStkgBTNeRO5HRQUDM52t1w6VNe9D2hmTLcdBWgs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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