SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9a5e19544cffbc429558cdcf117c545f242408e74b79fd637e5ae81b7fa5bb90' 
  AND token = '4czBNTbxGgHvqQbAApgaYoPldkEyncNuEE1644mqe1o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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