SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0ff16fd630549c9109caf114ba8f35d0720530660319490fd8dbf9beff8120a3' 
  AND token = 'N8poqjOvb/utYO16nTaQhMO9eS2OAm9zTSreWzjSzzA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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