SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6c4ea8d5f28027834f90aa53911ca462870cfd995e6d3b5ab4fa2de8107f8f6' 
  AND token = '6N/iEsQEbszaBAsdXepsfaw8gZ4r5M5Cu8nIuzyV5P4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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