SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b61b5d3df87cc5e4506c00f966213f0fd57eb427b84d5b141592c5f635246c9' 
  AND token = 'bDgQJpplhi0LZnR6vOxpoTBFJq+Go4knsYjvTvu0Cjg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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