SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8134cd068a510eec2a46fdfde5b69e8ec03aeaab9776c884fde281e2dec7ef6d' 
  AND token = 'd5BQwNkQsVKRtDL1oYZpefaYI8gKDTeecVICSqvAT10=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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