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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfc0e5d604e97bdc0050e8587d776d7486c4d0e8ddfcb3c146edaaa8f912cf14' 
  AND token = '/kVZolCPXd5+YCZNCSSBmlL7BXqvJeGz1g73CS/CTLQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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