SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35b8ece23e0cfe2b039541a29eab9dbeeb74547e7a37c5e794a1d3c91cde3aab' 
  AND token = '4FtApbwORDPgPPGwcFdIVK7tR1rk5TerNik9jw91TnA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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