SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c9ef13d234fec58eb3560672d3fd18662fd67509e385f60967620cd07a18d7b' 
  AND token = '3mI4CFMbyUJ6ppetvftEMStIlFAe6LWpk/CBHkwWeQ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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