SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a51abf5dd7bf8234654cc4519dc34f9d62ba9a85b915fe4c6f1ce6c07df93ba' 
  AND token = '55LKjWvPGTqHo2lNrjF7+308l/IcFMnpq5Es+5gizdU=' 
  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"
    }
  }
}