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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3842997ecec3c914274d178c891527a26568fc7a480f86c3bb540723bcff8209' 
  AND token = 'uEwZFIoFtMxCSkXc9Q21F5SHxkFIAn/HzNdYyuO9ApI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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