SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0e647555e1cc98872aee8c2c406cb3ab450f48a3e03ae164f24d0836b1dbc268' 
  AND token = 'f6LkjhuiFKjcWZzJumEFba+tD0AuUjIWzkQs0uTsK38=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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