SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a664f452e39ece7ffffa70504891025f1bfc130c09042e98e0ed654b0aad392d' 
  AND token = 'UDpJQOwdGXX4Y7cd+NIWdw+Q1/LLHQ1YwgiuKfMSADE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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