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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6fe1ec9fbb6a571786f7781673c4d59e82233fa2538a3e3aa47681843bb4fdc5' 
  AND token = 'yY3AskrwDDS39k4AZcWcmHqdihfQoRH3FSC7X+ltFQI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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