SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd5bf55e89924eaf0b1bb29afc8eedf6ec21bfa8de2ad809efe22da92cb9d5f79' 
  AND token = 'dQMTHe+5deLJ0mW89Z7mULEzyhg2g4nJWjq4+m3ij/Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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