SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b1b29a605418513e8f2a4329b6b62d233e1c6790cbd50836b32f694a3774fa0' 
  AND token = '+UZuwaMYSLskn8GweR2eRVLpVgPBIaHionJdZ2v5skM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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