SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4bb51853491623ec6be28c80f2aca7e3ea77955748fbfdced794c10e859fc2df' 
  AND token = 'vQQ7Jy+sZmJs7Z/jb/NlZ/ZBnPaes9WEoF0gBBvphGg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}