SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a6012799193f0223cde77381646c0071f5c5260423fe300554b80a2d604a1dd' 
  AND token = 'AFrPfckmSnaXfy9XlgxyI07JKHiFxkIIsaOs+bIPnVM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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