SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e12bc870f953cd19e98f642a7629ff1cdc5bbd3441485fdfa94fa4c079f6d458' 
  AND token = '6EORvUWju4w8XMbTuhAMbRYkEpWN9iGPFgScRPOnezQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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