SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd756a4da016996cb08a04e2eb263fed4a2df0c4c389915b178ce3222beaf06eb' 
  AND token = 'HieAT0HP7VgPYQznu/smIRFtQHrUIUswBFjuVq8EazU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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