SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c71114cd93656d3e487407025b4bfe6cc2219ce013fb1b02253e84d976fb549d' 
  AND token = 'S0i4c/4eIqDUMwkPQWWnTlr9K8eCSdOyNQBNreiqcvU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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