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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3e88e9edbf3a815e7676252f46259a13dbc27814c7ba9a0f5092afccc2f18174' 
  AND token = '3QHtTY7xBjkoniiNbEYA0zIoOlmgi0SQeeZq/GExWdE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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